A page from the Manual:

The Campaign Editor in the works:

A sample campaign with 5 scenarios to show all options
1. all surviving leaders at end of "Dear Santa" will arrive in Long road 1
2. all units surviving Long Road 1 are shifted to Long road 2
3. all units surviving Long Road 2 are shifted to Long road 3
4. all units surviving Long Road 3 will arrive in 'in the Fields'
5. No units surviving 'in the Fields' arrive in 'the Dike' . so 'the Dike' stands alone.
'the Dike' has no transition as it ends the campaign
more about shifting maps you find in this video:
Changed files in this update